This invention relates to a method of preparing feed grain compositions for livestock. More specifically, it relates to a process involving the fermentation of a mixture of animal wastes and grain.
Animal production based on confinement of animals in large groups means that animal wastes also are confined. This waste can be considered a raw material whose on-site concentration allows continuous collection and processing. For example, animal wastes contain sufficient nitrogen in the form of protein (ca. 20% of total N) and in forms readily convertible by microorganisms to protein (urea and ammonia nitrogen constitute ca. 30% of total N) to be potentially useful as a nutrient source for feeds.
Animal wastes have been collected and refed without further treatment to the same or different species, generally as a nitrogen source. These studies have been discussed by Anthony (J. Anim. Sci. 32: 4, 799-802, 1971) and extensively reviewed in detail by Smith ("Recycling Animal Wastes as a Protein Source," Symposium on Alternate Sources of Protein for Animal Production, Amer. Soc. Anim. Sci. and Committee on Animal Nutrition, Nat. Res., 1972; and "Nutritive Evaluations of Animal Manures," pages 55-74, In: G. E. Inglett, ed., Symposium: Processing Agricultural and Municipal Wastes, Avi Publishing Company, Westport, Connecticut).
In his report, Anthony stated that "it is detrimental to feed quality if manure is even partially decomposed by ubiquitous aerobic microorganisms."
In contrast to direct refeeding, feedlot manure has been ensiled (an anaerobic fermentation) with roughage (57 manure:43 hay, w/w; ca. 20% manure, dry basis) and termed Wastelage (Anthony, Proc., Conf. on Animal Waste Mangement, Cornell University, Ithaca, New York, pages 105-113, 1969; and Livestock Waste Management and Pollution Abatement, Proc. Int. Symposium on Livestock Wastes, Amer. Soc. Agri. Engineers, St. Joseph, Michigan, pages 293-296). The ensiled mixture fed at 40% of a corn ration afforded satisfactory gains, although feed:gain ratios are somewhat higher than with control rations. An anaerobic lactic fermentation of whole manure neutralized with anhydrous ammonia also has been reported (Moore and Anthony, J. Anim. Sci. 30: 2, 324, 1970), and acid treatment of the cellulosic fraction of manure to provide a substrate for yeast production has been proposed (Singh and Anthony, J. Anim. Sci. 27: 4, 1136, 1968).
We have found a method of preparing animal feed compositions comprising the steps
P1 a. mixing from 2 to 15 parts, dry weight basis (dwb) of animal feedlot waste (FDW) with 100 parts dwb of fragmented grain (FG) and an amount of water such that the resulting mixture contains from 35% to 45% moisture; and PA1 b. aerobically fermenting the mixture resulting from step (a) while submitting the mixture to a tumbling action for a time sufficient to obtain a pH in the mixture of from 4 to 5.
A major advantage of the above method is the simplicity of operation. Each step can be accomplished on the feedlot site in easily obtainable and relatively inexpensive equipment. Daily production of waste can be used up quickly so that the problems of waste accumulation are eliminated. The product, when dried to ordinary corn storage conditions, can be stored in the same manner as corn.
Another major advantage is that the fermentation is aerobic and does not require the controls necessary to anaerobic fermentations. No pH control is necessary.
Microorganism growth is selective to lactobacilli while coliform and other organisms found in feedlot waste are eliminated. Within a short time after fermentation begins, fecal odor disappears and is replaced by a more pleasant silage-like odor. Possible health and pollution hazards inherent in the waste are reduced in the early stages of fermentation. Most of the nitrogen contained in the waste is conserved while the waste is converted to a feed having more more desirable amino acid compositions.